International Journal of Applied Dental Sciences 2020; 6(2): 362-366

ISSN Print: 2394-7489 ISSN Online: 2394-7497 IJADS 2020; 6(2): 362-366 International journal of applied dental sciences © 2020 IJADS www.oraljournal.com and its prosthodontic implications Received: 14-02-2020 Accepted: 16-03-2020 Dr. Divya Puri, Dr. Pankaj Dhawan and Dr. Piyush Tandan Dr. Divya Puri Student, MDS, Department of Abstract Prosthodontics, Manav Rachna Tongue is muscular organ of the body located in floor of . It is usually a contributing factor for Dental College, Faridabad, retention and stabiliy of mandibular complete dentures. Therefore while fabricating a complete denture, it Haryana, India is important to understand the , size, position and classification of the tongue and surrounding musculature in order to achieve proper retention and stability of the complete denture. Dr. Pankaj Dhawan Professor and Head, Department Keywords: Tongue, denture retention, denture stability of Prosthodontics, Manav Rachna Dental College, Faridabad, Haryana, India 1. Introduction Tongue is muscular organ which is anchored to hyoid bone, mandible, soft , pharyngeal Dr. Piyush Tandan wall and styloid process in the oral cavity. It is readily associated with numerous vital oral and Professor, Department of maxillofacial functioning, such as- taste, mastication and deglutition, and takes part in sucking, Prosthodontics, Manav Rachna Dental College, Faridabad, swallowing, speech, receiving food into mouth, and articulation. Lack of any mentioned above Haryana, India activity may lead to severe impairment in socialization and patient’s quality of life. Also, tongue plays an important role in formation and production of effective speech by faciliatating formation of consonants and vowels by contacting specific part of the teeth, alveolar ridge or [1].

2. Anatomy of tongue The root of the tongue is attached to the hyoid bone and the mandible. The dorsum of the tongue is divided into an anterior 2/3rd and posterior 1/3rd, which are seperated by a faint V - shaped groove called as sulcus terminalis. Hence the anterior part is called the presulcal or oral

or papillary part and the posterior part is called the post sulcal or pharyangeal or glandular part. The limbs of the V shaped sulcus run anteriolaterally and forms a median foramen caecum (from where the thyroid has its origin) and ends with the palatoglossal arch on either side. The tip of the tongue forms anterior free end and lies behind the maxillary incisors at rest. The ventral surface of tongue is smooth and purplish in color and show a median mucosal fold

known as frenulum linguae. Deep lingual lie lateral to frenulum linguae and fringed [2] mucosal ridge known as plica fimbriata lies adjacent to it .

Corresponding Author: Dr. Divya Puri Student, MDS, Department of Prosthodontics, Manav Rachna Dental College, Faridabad, Haryana, India Fig 1: Lingual anatomy of tongue

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Development of tongue [3] The tongue develops in relation to the 1st to 4th pharyngeal arches in the floor of the developing mouth. It develops during 4th week of interuterine life. Each pharyngeal arch arises as a mesodermal thickening in the lateral wall of the foregut and grows ventrally to continue with that of the opposite side. The two lingual swellings arise from the ventral aspect of the first brachial arch and are partially separated from each other by another swelling that appears in the midline called the tuberculum impar. From here the epithelium proliferates to form a downgrowth giving rise to the thyroid gland and is marked by a depression called the foramen caecum. Another, midline swelling is seen in relation to the medial ends of the second, third and fourth arches. This swelling is called the Fig 4: Scheme to show the origin of different parts of the tongue hypobranchial eminence or copula of His. It is subdivided into a cranial part related to the second and third arches (called the Keeping in mind the embryological origin, the lingual branch copula) and a caudal part related to the fourth arch that later of the mandibular nerve, the post-trematic nerve of the first forms the epiglottis arch innervates the anterior two thirds of the tongue while the chorda tympani nerve, the pre-trematic nerve carries the taste sensation. The glossopharyngeal nerve, the nerve of third arch, supplies the posterior one-third of the tongue. The superior laryngeal nerve, the nerve of the fourth arch, supplies majorly the posterior-most part of the tongue The mucosa of tongue is derived from endoderm of foregut. The musculature of the tongue is derived from the occipital myotomes hence is supplied by the hypoglossal nerve, except palatoglossus which is supplied by pharyngeal plexus.

Papillae of tongue

These are small finger like projections of lamina propria that Fig 2: Different parts involved in development of tongue elevates the epithelium. They are predominantly found on the anterior two third of the tongue giving it, its characteristic The tuberculum impar fuses with the two lingual swellings to roughness. These are of four types: circumvallate, fungiform, form the anterior two third of the tongue, thus said to be filiform and foliate papillae. Circumvallate papille being the derived from the first mandibular arch. Whereas the cranial largest of all are seen immediately in front of sulcus part of the hypobranchial eminence (copula) forms the terminalis whereas others are located around the tip and posterior one-third and hence is derived from third brachial margins of the tongue. arch. The mesoderm of the second arch gets buried below the surface while the mesoderm of third arch grows over it to fuse with the mesoderm of the first arch. The posterior one-third of the tongue is thus formed by third arch mesoderm and is derived from the fourth mandibular arch.

Fig 5: Papillae of tongue

Muscles of tongue Fig 3: Scheme to show how the second arch is buried by overgrowth A median fibrous septum divided the tongue into right and of the third arch, during development of the tongue left halves. Each half contains two sets of muscles, which are intrinsic and extrinsic. The intrinsic muscles are seen in the The anterior two thirds and posterior one-third of tongue are upper portion of tongue and is attached to submucous fibrous demarcated by an inverted V-shaped groove called as sulcus layer and the median fibrous septum. There are four paired terminalis. intrinsic muscles and are named by the direction in which

~ 363 ~ International Journal of Applied Dental Sciences http://www.oraljournal.com they travel: The Superior Longitudinal, Inferior Longitudinal, posterior-most part of tongue is innervated by Internal Transverse muscle and Verticalis. These muscles alters the Laryngeal branch of the Vagus nerve. shape and size of the tongue. The extrinsic muscles are four in number, and connects tongue to mandible via Genioglossus, Arterial and venous drainage to hyoid bone via Hyoglossus, to styloid process via Major portion of the tongue is supplied by the lingual , a Styloglossus and the palate via Palatoglossus. These are branch of the external carotid artery except the root of the commonly associated with retraction, elevation and tongue which is supplied by tonsillar artery, a branch of the depression of the tongue surface. facial artery. Deep lingual draines the tongue. It starts from the tip on inferior surface of tongue, near anterior border of hyoglossus, joining the and forms vena commitans nervi hypoglossi which further drains into and internal .

Lymphatic drainage Submental and submandibular lymph nodes drains the tip and the anterior two thirds of the tongue respectively whereas the posterior one third is drained by juglo-omohyoid lymph nodes. The upper deep cervical lymph nodes drains the posterior most area of tongue.

Fig 6: Muscles of tongue

Movements of tongue [4] The tongue is used in sucking, chewing, swallowing and speaking, pursing and licking of . The intrinsic muscles alters the shape of the tongue whereas the extrinsic muscles stabilizes the organ by their contraction and alters its position and shape too.

Alteration of shape: The transverse muscle narrows the tongue and elongates it. With simentaneous contraction of the verticalis muscle, the convexity of tongue is flattened and broadened. The contraction of longitudinal fibers of inferior Fig 7: Lymphatic drainage of tongue longitudinal muscle makes the tongue concave from front to back while the contraction of the vertical fibers produces a Manifestations of systemic diseases on tongue [6] midline groove helping in first stage of swallowing. Tongue is examined carefully for various systemic diseases for its oral manifestations. In case of Iron deficiency anaemia Alteration of position: Styloglossus retracts the tongue. it represents as Atrophic glossitis, due to flattening of the Hyoglossus draws the sides of the tongue downward. The papillae on the dorsum of the tongue accompanied with a mylohyoid muscle alters the position of tongue. The lowest tenderness or a burning sensation. While in Pernicious fibers of genioglossus contracts the back of tongue and it is Anemia it appears as “Magenta tongue” due focal or diffuse extruded. erythema of the tongue and mucosal atrophy. In autoimmune diseases like Sjo ̈ gren Syndrome its appears Table 1: Location and Effect of the Musculature Limiting the Lower “bald” or even “cobblestone-like” tongue due to atrophy of Denture Space [5] the papilla. While in Kawasaki Disease, its seen as Strawberry tongue due to swelling of papillae on the surface of the tongue and intense erythema of the mucosal surfaces. In Scleroderma it appear smooth and can lose mobility. In Systemic Lupus Erythematosus it appears with Multiple granulomatous- appearing ulcerations on the tongue dorsum. In endocrinal disorders like Diabetes Mellitus it is seen as central papillary atrophy of the tongue dorsum. In viral diseases like HIV- AIDS [7] it appears in form of Oral hairy leukoplakia which is categorized as a white lesion which is usually present on the lateral surface of tongue. Innervation of tongue In the anterior 2/3rd, the lingual nerve, a branch of the Classification of tongue and its prosthetic implication mandibular nerve is responsible for general sensation while A) Functional tongue classification according to degree [8] the chorda tympani nerve a branch of facial nerve is of activity by Barnett Kessler was classified into responsible for taste sensation. The posterior 1/3rd of the four types based on working range of tongue tongue is supplied by the glossopharyngeal nerve whereas the The Occupational tongue: Apply to those people whose ~ 364 ~ International Journal of Applied Dental Sciences http://www.oraljournal.com activities require increased tongue action. E.g. jurists, overextended and vice versa. Displacement of the tray when teachers, lecturers, preachers, musicians. the tongue is raised toward the could mean that the anterior portion or lingual frenum is overextended. The Still tongue: Also called Passive tongue. Have limited tongue activity. Could be due to injury, deformity etc. E.g. B) Border molding ankyloglossia Lingual frenum and sublingual flange- (premolar to premolar) The patient is instructed to wipe his lower from side to The Normal tongue: It is of prosthodontist’s delight. Tongue side with the tongue tip and then asked to protrude the tongue exhibit normal function and range of movements. to determines the height of the anterior lingual flange and The Habitual tongue: It refers to the disturbing powerful records the frenum. Then the patient is asked to push his movements of the tongue developed due to habit. Base of the tongue forcefully against the front the front part of the palate tongue is thick and powerful and imposes dislodging forces to develop the thickness of the flange. on the denture. According to him tooth arrangement should be done in a Mylohyoid portion manner so that it does not affects the functioning of the To mould the right lingual flange the patient is instructed to tongue. The base of the tongue is frequently “hooked” by the bring the tongue in contact with the left and vice versa. lower second molars resulting in unstable lower dentures. This determines the length of the flange in this region. The Therefore, lower second molars in complete dentures should flange in this region must slope towards the tongue to allow be arranged without hindering the tongue movement. for the action of the mylohyoid.

B) Classification of tongue position according to wright [9] Retro mylohyoid portion Distal most part of the lingual flange which rises up towards the retromolar pad is limited by the retro mylohyoid curtain. The patient is asked to wide open the mouth, protrude the tongue and then close the jaw against resistance from the operators thumb.

C) Occlusal plane The occlusal plane must lie at the lateral border of the tongue, if higher may result in unstable denture due to lateral tilting forces directed against the teeth.

D) Jaw relation The mandibular wax rim and consequently the occlusal plane is at 2/3rd the height of the retromolar pad. The occlusal plane must lie at the lateral border of the tongue. While recording vertical relation the tongue must be in its normal position. While training the patient to close in centric, the patient may be asked to touch his tongue to the palate and swallow.

E) Teeth arrangement The mylohyoid ridge is a reliable guide. The lingual cusps of the molars are aligned in harmony with the mylohyoid ridge, never lingual to it. Placing them far too lingually can cause: Class 1 position has the most favourable prognosis as the cramping of the tongue, tongue biting and instability of the floor of the tongue is at a higher level to cover the lingual denture during tongue function. Also, in order to balance the flange of the denture producing a border seal. Whereas class forces of the tongue pressing outwards with the forces of the II and III are unfavourable tongue positions as they drop the and lips pressing inward, neutral zone technique was level of floor of mouth hence providing an inadequate lingual employed. Failure to recognize the importance of ideal tooth seal and extension of flange resulting in overextension and position, flange form and contour often results in dentures dislodged denture at time of tongue movement. which are unstable and unsatisfactory while those in harmony with neuromuscular function are successful and stable Tongue also plays important role in following prosthetic dentures [10, 11]. procedures A) Tray selection F) Speech considerations: Sounds affected by the tongue While seating the mandibular tray in position, the patient is [12] asked to lift the tongue and bring it forward to avoid ▪ Linguo-dental: They are produced by the contacting the entrapping it below the tray. tip of the tongue against palatal surface of the upper The lingual borders of the tray are checked by functional anterior teeth. Eg:Th movements of the tongue by bring the tongue straight out. If ▪ Linguopalatal: They are produced by the tongue and the tray rises vigorously from the posterior end, the palate. Eg: D,N,L,T. distolingual flange could be overextended, thus has to be ▪ Alveolar sounds: They are produced by the tongue reduced. placed against anterior portion of hard palate (D,T). Displacement of the tray when the tongue is moved to the ▪ Nasal: (N, NG) right side would mean that the left side (mylohyoid portion) is

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Excessive denture base thickness in palatal surface causes loss 3. Textbook of Human Embryology- Inderbir Singh 7th of tongue room and decreased volume of air. Expression of Edition linguopalatal and linguoalveolar sounds may be difficult. If 4. Srinivas K, Jyoti Gupta, Ratnakar P, Arti Saluja Sachdev, the teeth are placed far too lingually, or the arch is too narrow Vasu Saxena, Taseer Bashir. Anatomy of tongue - A the tongue will be cramped resulting in faulty phonation, review article International Journal of Multidisciplinary affecting linguoalveolar and lateral lingual sounds. Research and Development. 2014; 1(7):124-125. 5. Luthra RP, Renu Gupta, Savisha Mehta, Reena Sirohi, G) Polished surface contour Naresh Kumar. Neuromuscular system and complete Martonet [13] emphasized that the stability of lower denture dentures-A review. Journal of Advanced Medical and depends upon the position of the tongue as it was considered Dental Sciences Research. 2015; 3(4):113-6. to be a more powerful muscle than the lips and cheeks. It 6. Nadim M Islam, Indraneel Bhattacharyya, Donald M. exerts a force of 16.4 Psi [14], while the lips and cheeks exerts Cohen. Common Oral Manifestations of Systemic only 4.3 Psi [15]. Therefore, when molding of the external Disease. Otolaryngol Clin N Am. 2011; 44:161-182. contours was considered, the lingual surface was the surface 7. Pala A, Chowbey R, Sonvanshi N, Patel D, Shah A, choice. Hence care must be taken while contouring the lingual Venkatesh A. A Review on Oral Manifestations of surface as its influence can mitigate against stability. Systemic Diseases. Int J Oral Health Med Res. 2016; 2(6):131-132. H) Food trough formation and mastication 8. Barnett Kessler. An analysis of the tongue factors and its The opening and closing movements of the mandible during functioning areas in dental prosthesis. 1955; 5(5):629-35. mastication is initiated by the neuromuscular movement of the 9. Essentials of complete denture prosthodontics- Winkler, tongue [16]. While mastication, some of the food may escape 3RD Edition out from the premolar region and may falls into the buccal or 10. Dawson PE. Functional Occlusion from TMJ to Smile lingual space which is then retrieved by the buccinator and the Design. St. Louis: Mosby, 2007. tongue, respectively. The fixation of the modiolus on the 11. 20. Beresin VE, Schiesser FJ. The neutral zone in buccal surface of the lower first premolar initiates the complete dentures. J Prosthet Dent. 2006; 95(2):93-100. posterior movement of food by the cheek along the tongue 12. Phonetics and tongue position to improve mandibular further facilitating deglutition. denture retention. J Pros Dent. 2007; 98(5):344-7. 13. Martonet AL. Clinical applications of concepts of functional anatomy and speech science to complete denture prosthodontics. Sept-Oct J Prosthet Dent. 1962; 12(5):817-34. 14. Rinaldi P, Sharry J. Tongue force and fatigue in adults. J Prosthet Dent. 1963; 13(5):857-65. 15. Kydd WL. Maximum forces exerted on the dentition by the perioral and lingual musculature. J Am Dent Assoc. 1957; 55(5):646-51. 16. Wright CR. Evaluation of the factors necessary to develop stability in mandibular dentures. J Prosthet Dent. 2004; 92(6):509-18.

Conclusion Tongue is an integral part of the oral anatomy. Its nature as such in prosthodontics has been controversial due to its anatomy and action on the lower dentures. It is imperative that the prosthodontist have a proper knowledge of the anatomical, functional, physiologic aspects of the tongue so as to rehabilitate the patient to the optimum level possible.

References 1. Rothman R. Phonetics consideration in denture prosthesis. J Prosthet Dent. 1961; 11:214‐23. 2. Chaurasia’s BD. Human anatomy Vol 3, 4th edition. ~ 366 ~